The rationale of this protocol is to characterize the local and sytemic immune response of normal individuals to intradermal administration of a replication deficient adenovirus type 5 gene transfer vector (Ad5CMV.Null2). A replication deficient Ad5CMV.Null2 vector will be administered by the intradermal route to healthy individuals. Over time, blood samples and lung epithelial lining fluid (ELF) samples as well as the site of the Ad5 vector administration will be evaluated for the presence of immune and inflammatory parameters relevant to the Ad5-vector. At the end of the study the following questions will be answered: Following intradermal administration of the vector, do Ad-specific neutralizing antibodies develop systemically (serum) and in lung ELF?; Does intradermal administration of the Ad vector evoke Ad-specific cytotoxic T-lymphocytes (CTL) (in blood and/or lung) which will recognize autologous cells infected with the Ad vector?; Do the humoral and cellular immune responses evoked by intradermal administration of Ad in blood differ from that in lung?, and Does intradermal administration of and Ad vector evoke local or systemic imflammation?